Structure and manufacture of abrading tool having suction system

ABSTRACT

An abrading tool having an aspirator for creating a partial vacuum acting to withdraw abraded particles to a collection location. The aspirator includes a conduit forming a passage into which air and entrained particles are drawn through a predetermined opening, with air inlet means directing a primary flow of air into the passage and across the opening to induce the desired movement of the particles.

United States Patent 1191 Hutchins [4 June 11, 1974 [5 1 STRUCTURE AND MANUFACTURE OF ABRADING TOOL HAVING SUCTION SYSTEM [76] Inventor: Alma A. Hutchins, 49 N. Lotus Ave., Pasadena, Calif. 91 107 22 Filed: Aug. 21,1972

21 Appl, No.: 282,457

[52] U.s.C1 ..51/170MT,5l'/273,51/356 51 Int. Cl 1324b 23/00 [58] Field ofSearch 51/170 R, 170 PT, 170 T, 51/170 TL, 170 BB, 170 MT, 273, 275, 356;

[56] References Cited UNITED STATES PATENTS Mueller; ..'.....5l/273 1,958,354 5/1934 Stephens 4l7/l98 x 2,000,930 5/1935 De Nagy 51/170 T 2,764,852 10/1956 Emmons 51/273 x Primary Examiner-Donald G. Kelly Assistant Examiner-Mark S. Bicks Attorney, Agent, or Firm-William P. Green [5 7 ABSTRACT An abrading tool having an a'spirator for creating a partial vacuum acting to withdraw abraded particles to a collection location. The aspirator includes a conduit forming a passage into which air and entrained particles are drawn through a predetermined opening, with air inlet means directing a primary flow of air into the passage and across the opening to induce the desired movement of-the particles.

12Claims, 9 Drawing Figures STRUCTURE AND MANUFACTURE OF ABRADING TOOL HAVING'SUCTION SYSTEM CROSS REFERENCE TO RELATED APPLICATION Certain features of the present abrading tools have been disclosed and claimed in my copending application Ser. No. 213,018 filed Dec. 28, 1971 on Abrading Tools Having Suction System For Collecting Abraded Particles...

BACKGROUND OF THE INVENTION bag. In the preferred arrangements shown in the draw- SUMMARY OF THE INVENTION Thepresent invention relates to improvements in abrading tools of the above discussed type, and particularly to tools having an improved aspirator arrangement for maximizing the amount of vacuum which can be created by the energy from a particular primary stream of air. To attain this result, the aspirator utilizes the primary stream energy in a most direct and positive manner. optimizing the interaction between the primary and secondary streams, and the efficiency with which the energy of the primary stream is utilized, and accomplishing all of this in an overall system which leaves the particle path through the aspirator very open and unobstructed.

The aspirator may include a conduit containing and forming a passage through which the particles flow toward a collectionlocation, with an opening being aspirator through an inlet, which is constructed and po-.

sitioned to emit a high velocity flow of the primary air essentially across the mentioned opening, to thus very directly and positively induce the desired flow of particles through the device. The passage within the conduit may be given a non-circular cross section, desirably in a relation making the passage relatively narrow in one direction and of greater dimension in another perpendicular direction, so that the air flow through the passage maybe very closely adjacent the discussed opening to further enhance the aspirator action. This noncircular cross-section may be provided by utilizing a tube having a partially flattened portion within which the non-circular passage is contained, and into which the particles flow through the discussed opening. The

inlet for the primary flow of air maybeformed within another tubular part, which projects into the main conduit or tube and may also be flattened somewhat. This latter tube may be closed at one end, and apertured along an edge of its flattened portion to emit the primary air stream into the conduit. Certain features of method novelty of the invention reside in the manner offorming the aspirator of such partially flattened parts.

BRIEF DESCRIPTION OF THE DRAWING The above and other features and objects of the invention will be better understood from the following detailed de'scriptionof the typical embodiments illustrated in the accompanying drawings in which:

FIG. 1 is in part a side elevational view and, in parta centralvertical section view of a sanding tool con structed in accordance with the invention;

FIG. 2 is an enlarged fragmentary view of the aspirator of FIG. I, and taken on line 2-2 of FIG. 1;

FIG. 3 is a bottom view of the aspirator taken on line 33 of FIG. 1;

FIG. 4 is an enlarged sectiontaken on line 4-4 of FIG. 2; I

FIG. 5 is a horizontal section taken on line 5-5 of FIG. 4;

FIG. 6 is a fragmentary vertical section taken on line 6- 6 of FIG. 2; I v

FIG. 7 is an exploded perspective view of the two parts. of the aspirator assembly;

FIG. 8 is a view similar to a portion of FIG. 7, but showing a variational form of the invention; and

FIG. 9 shows another variational arrangement having a circular sanding head.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The abrading tool 10 of FIG. 1 is typically illustrated as constituting a power operated sander, which functions to abrade and smooth a typically planar work surface represented at 11. Particles abraded from the work surface are withdrawn by suction to adust collec tion bag represented at 12.

The tool 10 includes a portable: body 13 having two handles 14 and 15 by which a user canholdthe tool and manipulate it overthe'work surface 11 during a sanding operation. The lower portion of the body may fonn a plate 16 which extends horizontally in the FIG. 1 position of the tool and'may be of rectangular horizontal configuration with a depending peripheral flange 17 extending downwardly therefrom. At the center of this plate-like portion 16, the bodlyl3 has an upstanding hollow portion 18 which carries the previously mentioned handle 14 and contains an inner motor 19 whose downwardly projecting driven shaft 20 turns about a vertical axis 21. Though it is contemplated that motor 19 may be of any convenienttype, it is in most instances preferably a vane type motor having an outer cylindrical non-rotating housing part 22 fn'red'to body 13 and containing a rotor 23 located eccentricallywithin a cylindrical chamber in part 22 and mounted to tum relative thereto about axis 21-. A series of circularly spaced radially extending vanes 24 movably con tained within slots in rotor 23 defilnewiththe rotor and stator a series of compartments 251 which change progressively in size as the rotor turns. Compressed air is fed to motor 19 from a source 26, and passes to the motor through passages 27 in handle 14, under the control of a finger actuated trigger valve 28. The air in entering the interior of the motor housing, and in being directed against the vanes of the rotor, passes through a restriction represented diagrammatically at 29 in FIG. 1, which gives the compressed air an extremely high velocity as it enters the motor and impinges against the vanes.

After the air thus admitted to the motor has driven the rotor, the compressed air is exhausted from within housing part 22 through a discharge opening 30 formed in the side of part 22 and communicating through a flexible hose 31 with an aspirator 32 which will be discussed in detail at a later point in this description. The air leaving motor 19 and entering the aspirator is still at a substantially super-atmospheric pressure, e.g., about 70 pounds per square inch, to attain an effective aspirator action.

Beneath plate-like portion 16 of the body and parallel thereto, the body 13 carries a shoe assembly 33 which is driven orbitally about axis 21 by motor 19 and carries a rectangular sheet of sandpaper or other abrasive material 34 having an abrasive undersurface for contacting work surface 11. This shoe structure or movable unit 33 may include a rigid shoe element 35 typically formed of sheet metal or the like and of rectangular horizontal outline. Element 35 carries a correspondingly rectangular pad assembly 38 at its underside, which includes a layer of resiliently deformable rubber or other elastomeric material 39 adhered by an appropriate cement to a more rigid upper sheet metal plate 40 covering the upper side of cushion 39. Two releasable spring pressed clips 41 carried by element 35 releasably retain opposite ends of the sandpaper sheet 34.

To drive the assembly 38 and carried sandpaper sheet orbitally about vertical axis 21, the motor shaft 20 has a lower cylindrical eccentric portion 43, having a vertical axis 44 which is parallel to but offset laterally from the main vertical axis of rotation 21 of the shaft and rotor. This portion 43 of the shaft is connected to the inner races of a pair of ball bearings 45, whose outerraces are fixed to shoe element 35 by reception within a hollow housing 46 attached rigidly to the shoe. Consequently, rotation of shaft 20 about axis 21 acts through the eccentric 43 of theshaft to move shoe 35 and the carried pad assembly 38 and sandpaper 34 orbitally about axis 21 to perform a sanding operation. During such movement, however, the shoe and carried parts are held against rotation about axis 21 by appropriate means typically including four resilient essentially vertical connector posts 47, formed of rubber or other elastomeric material, and which are sufficiently stiff to retain the shoe in essentially fixed orientation with respect to body 13 while at the same time permitting slight captive orbital movement of the shoe relative to the body. The upper and lower ends of the posts can be connected to portion 16 of the body and to the shoe element 35 in any appropriate manner, as by screws 48 connected into nuts 49 embedded in the elastomeric material of the posts.

The deformable cushion 39 which backs up sandpaper sheet 34 contains several spaced apertures 52 extending vertically upwardly through the cushion and registering with corresponding apertures 53 formed in the sandpaper directly opposite the apertures or passages 52. These apertures 52 and 53 conduct air and abraded particles from surface 11 upwardly into a horizontal passage or passages 54 formed in the upper face of cushion 39 and closed at their upper sides by plate 40. The air and particles are conducted horizontally through passages 54 to the location of a short tube 57, which is carried by plate 40 and projects upwardly therefrom to lead the air and particles into a connected flexible vertical tube 58 leading to aspirator 32. The upper end of the short hose or tube 58 is connected to a downwardly projecting short tube 59 carried by the aspirator, with tube 58 being adapted to flex in correspondence with the orbital movement of the shoe relative to the body.

To now describe the structure of the aspirator 32 in detail, this aspirator typically includes two preferably metal parts 60 and 61 which may be fabricated to the shapes illustrated in FIG. 7 and then brazed or otherwise secured together to form the complete aspirator. Element 60 is a conduit, which may be formed from rigid initially straight cylindrical metal tubing, having a portion 62 which is partially flattened to form a noncircular part of the conduit. The remainder 63 of this conduit is undeformed and retains its initial tubular straight cylindrical configuration, centered about the axis 64 of the figures. The cross-sectional configuration to which the portion 62 of conduit 60 is deformed is illustrated in FIG. 4. As seen in that figure, the portion 62 of conduit 60 is flattened so that the inner passage 65 therethrough has a reduced vertical height h which is much smaller than its horizontal width w, the latter desirably being at least about three times and preferably at least four times as great as the former. More specifically, this cross-section may be defined by upper and lower horizontal parallel walls 66 and 67 and two opposite side walls 68 and 69 which are curved or rounded as shown in FIG. 4. The portion 62 as previously indicated initially has the same tubular crosssection as portion 63 of the conduit, but is deformed as shown, from the end edge 70 of portion 62 to a location 71, beyond which the tube progressively flares at 72 to the circular cross-sectional shape of portion 63.

At a location near the end edge 70 of conduit 60, the bottom wall 67 contains a preferably circular opening 73, within which the upper horizontal edge portion of the previously mentioned short vertical tube 59 is secured in fixed and peripherally sealed relation, as by brazing tube 59 within opening 73. This tube projects downwardly through a correspondingopening 74 in horizontal plate portion 16 of body 13, with the bottom wall 67 of portion 62 of conduit 60 resting on and being brazed rigidly to the upper surface of body portion 16. Thus, the particles and air drawn upwardly through tube 58 flow upwardly through the opening 73 formed by the upper end' of tube 59 into conduit 60.

The second main element 61 of the aspirator is also fabricated from an initially straight cylindrical rigid metal tube, whose portion 75 is left undeformed and of the initial tubular shape while its portion 76 is partially flattened and deformed to an angular relationship with respect to portion 75 to fit into the rear portion of conduit 60 in the relation illustrated in the figures. The cross-section of the partially flattened portion 76 of part 61 is illustrated best in FIG. 6, which shows that the upper and lower generally parallel horizontal walls 77 and 78 of this tube portion are received in proximate relation to and parallel to upper and lower walls 66 and 67 respectively of portion 62 of conduit 60. The

side wall 69 of portion 62 of conduit is cut away at 77' to pass part 61 therethrough, and the part 61 is then brazed or otherwise rigidly secured and sealed to portion 62 entirely about the cutaway 77 and entirely about the. periphery of the rear edge of part 60,in a manner preventing the escape of any air from part 61 in any direction other than into the interior of conduit 60 and through that conduit to collection bag 12. As seen in FIG. 3, the deformed portion 76 of part 61 is positioned to overlie approximately one-half of the opening formed by tube 59, and the transverse edge wall 177 of part 61 is apertured to emit a flow of the primary air rapidly in a rightward direction as viewed in FIGS. 1 and 6, parallel to axis 64, and through conduit 60 to its discharge end. Desirably, a number of horizontally spaced small apertures 79 facing parallel to axis 64 are formed in edge wall 177, to emit several high velocity jets or streams of air parallel to that axis and essentially across theunobstructed portion of the opening formed by the upper end of tube 59. This flow of air is generally horizontal and therefore perpendicular to the upward direction in which the opening 73' formed at the upper end of tube 59 faces. That opening is of course in effect reduced in size by, or partially closed by, the portion of part 61 which extends across approximately one-half of tube 59. The inlet portion of element 61 is connected to the previously mentioned flexible tube 31 to receive discharge air from the motor.

To summarize the operation of the device of FIGS.

1 to 7, motor 19 oscillates shoe assembly 38 and the sandpaper orbitally about axis 21 to perform a sanding operation, with the air discharged from motor 19 passing into aspirator 32 through element 61. This air discharges through apertures 79 horizontally across the approximately semi-circular upwardly facing opening formed at at the upper end of tube 59, with the jets of air from the apertures 79 sweeping across that opening in a manner creating a very effective suction effect drawing air and carried abraded particles upwardly through the opening 80 into the interior of conduit 60 for discharge therefrom through a flexible hose 81 to bag 12, in which the particles are entrapped while the air escapes through the porous walls of the bag to the atmosphere. The particles in flowing to the aspirator move upwardly through apertures 52 and 53' in the shoe and sandpaper and through passage or passages 54 to flexible tube 58 which leads into the aspirator.

The total area of apertures 79 through which the primary air emits across the suction opening 80 should desirably have a critical relationship to the size of the most restricted portion 29 leading into the inlet side of the air motor. If apertures 79 are given too great an area, this tends to reduce the velocity of the air leaving the apertures and reduce the suction created by the aspirator. Conversely, if the apertures 79 are too small, they may create too great a back pressure in the motor tending to reduce its operational effectiveness. For these purposes, it is found desirable that the total area ofapertures 79 be for best results between about 3% and 5 times as great as the area at the most restricted portion 29 of theinlet passage to the motor, and optimally approximately 4 times that size.

FIG. 8 shows fragmentarily at 61:: a variational form of the part 61 of FIG. 7. In FIG. 8, the part 61a is identical with part 61 except that a horizontally elongated slot 79a has been substituted for the series of spaced apertures 79 of the first form. Like the aperture 79, this slot faces in a direction parallel to the main axis 64 of conduit 60, and in all other respects the arrangement of FIG. 8 may be the same as that described in FIGS. 1 to 7.

FIG. 9 shows another type of sander embodying the invention and in which a handle body 81 contains an air motor 82 having a driven shaft 83 with an eccentric portion 84 rotatably connected by bearings 85 to a head 86 which mounts a circular backing structure 87 to which a circular disc 88 of sandpaper is adhered. Thebacking structure 87 and sandpaper contain aperturesat 89 through which "abraded particles are drawn upwardly from the surface of the work 90. Body 81 rigidly carries a hollow downwardly projecting generally annular skirt 91, which may in turn carry an annular downwardly flaring typically elastomeric shroud 92 en-' circling the orbitally driven backing plate 87 and sandpaper, to form an enclosed space about the backing plate and sandpaper through which particles may be drawn upwardly not only from apertures 89 but also from the space 93 about the backing plate. The skirt 9] has a top horizontal wall 94 projecting laterally or horizontally beyond the adjacent portion of body 81, and

to which an aspirator 32b is rigidly mounted. This aspirator may be identical with the aspirator 32 of the first form of the invention, except that the short tube 59 of FIG. 1 is omitted. The bottom horizontal wall 67b of conduit 60b, corresponding to wall 67 of FIGS. 1 to 7, contains a circular opening corresponding to opening 73 of bottom wall 67 of the first form of the invention, and registering with a corresponding circular opening 74b'in wall 94 of the skirt 91, to pass air and particles upwardly into the conduit under the aspirator action produced by the emission of high velocity primary air across the upper side of that opening, as discussed in detail hereinbefore.

It will of course be understood that the aspirator may also be applied to other types of tools in addition to those specifically disclosed herein and illustrated in FIGS. 1 and 9.

While certain specific embodiments of the present invention have been disclosed as typical, the invention is of course not limited to these particular forms, but rather is applicable broadly to all such variations as fall within the scope of the appended claims.

I claim:

l. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said first mentioned passage having a portion in the vicinity of said opening which is relatively narrow in a first direction transversely of its length and is wider in a second direction transversely of its length.

2. A portable abrading tool as recited in claim 1, in which said first mentioned passage and said conduit change to an essentially circular cross section at a location downstream of said opening.

3. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means defining said inlet passage including means forming a plurality of spaced apertures located essentially opposite said opening and emitting aplurality of spaced streams of primary air across the opening.

4. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary How of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage gener' ally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means forming said inlet passage including a tubular inlet part projecting to a location essentially opposite said opening and having a wall containing one or more apertures through which primary air is emitted across said opening.

5. A portable abrading tool comprising a body structure with the primary flow, said means forming said inlet passage including a tubular inlet part extending into said conduit to a location essentially opposite said opening and having one or more apertures emitting primary air across'said opening.

6. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a-location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means forming said inlet passage including an inlet tube having a partially flattened portion adjacent said opening with a wall containing one or more apertures emitting primary air across the opening.

7. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generture, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixticles through the opening into said passage for admixture with the primary flow, said 'means forming said inlet passage including a tubular part having a partially flattened portion closed at one end and having an edge wall containing one or more apertures emitting primary air across said opening.

8. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said conduit having a partially flattened portion opposite and beyond said opening defining a portion of said first mentioned passage which is of non-circular cross section and has a relatively narrow width in the direction in which said opening faces into the passage and a greater width generally perpendicular to said direction, said means forming said inlet passage including a tubular part projecting into said flattened portion of said conduit and emitting primary air thereinto across said opening.

9. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and.

entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said conduit having a partially flattened portion opposite and beyond said opening defining a portion of said first mentioned passage which is of non-circular cross section and has a relatively narrow width in the direction in which said opening faces into the passage and a greater width generally perpendicular to said direction, said means forming said inlet passage including a tubular part having a partially flattened portion projection into said partially flattened portion of said conduit generally transversely thereof and to a location adjacent said opening and having a closed end and aperture means formed in a side edge of said flattened portion of said tubular part at a location emitting primary air across said opening.

10. A portable abrading tool as recited in claim 9, in which said aperture means include a plurality of spaced apertures formed in said side edge of said tubular part and emitting a plurality of streams of primary air across said opening.

11. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said first mentioned passage having a non-circular cross section in the vicinity of said opening which is elongated in a relation giving said first mentioned passage a narrow width in a predetermined direction in which the opening faces into said first mentioned passage and a substantially greater width generally perpendicular to said direction. 1

12. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first men 7 ticles through the opening into said passage for admixture with the primary flow, said first mentioned passage having a non-circular cross section in the vicinity of said opening which is elongated in a relation giving said first mentioned passage a narrow width in a predetermined direction in which the opening faces into said first mentioned passage and a substantially greater width generally perpendicular to said direction, said first mentioned passage and conduit having said noncircular cross section for a substantial distance beyond said opening and then changing progressively to an essentially circular cross section. 

1. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said first mentioned passage having a portion in the vicinity of said opening which is relatively narrow in a first direction transversely of its length and is wider in a second direction transversely of its length.
 2. A portable abrading tool as recited in claim 1, in which said first mentioned passage and said conduit change to an essentially circular cross section at a location downstream of said opening.
 3. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means defining said inlet passage including means forming a plurality of spaced apertures located essentially opposite said opening and emitting a plurality of spaced streams of primary air across the opening.
 4. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means forming said inlet passage including a tubular inlet part projecting to a location essentially opposite said opening and having a wall containing one or more apertures through which primary air is emitted across said opening.
 5. A portable abrading tool comprising a body stRucture, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means forming said inlet passage including a tubular inlet part extending into said conduit to a location essentially opposite said opening and having one or more apertures emitting primary air across said opening.
 6. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means forming said inlet passage including an inlet tube having a partially flattened portion adjacent said opening with a wall containing one or more apertures emitting primary air across the opening.
 7. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said means forming said inlet passage including a tubular part having a partially flattened portion closed at one end and having an edge wall containing one or more apertures emitting primary air across said opening.
 8. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means definIng an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said conduit having a partially flattened portion opposite and beyond said opening defining a portion of said first mentioned passage which is of non-circular cross section and has a relatively narrow width in the direction in which said opening faces into the passage and a greater width generally perpendicular to said direction, said means forming said inlet passage including a tubular part projecting into said flattened portion of said conduit and emitting primary air thereinto across said opening.
 9. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said conduit having a partially flattened portion opposite and beyond said opening defining a portion of said first mentioned passage which is of non-circular cross section and has a relatively narrow width in the direction in which said opening faces into the passage and a greater width generally perpendicular to said direction, said means forming said inlet passage including a tubular part having a partially flattened portion projection into said partially flattened portion of said conduit generally transversely thereof and to a location adjacent said opening and having a closed end and aperture means formed in a side edge of said flattened portion of said tubular part at a location emitting primary air across said opening.
 10. A portable abrading tool as recited in claim 9, in which said aperture means include a plurality of spaced apertures formed in said side edge of said tubular part and emitting a plurality of streams of primary air across said opening.
 11. A portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said first mentioned passage having a non-circular cross section in the vicinity of said opening which is elongated in a relation giving said first mentioned passage a narrow width in a predetermined direction in which the opening faces into said first mentioned passage and a substantially greater width generally perpendicular to said direction.
 12. A Portable abrading tool comprising a body structure, a unit movable relative to said body structure to abrade a work surface, a motor for moving said unit to abrade the work surface, and an aspirator through which a primary flow of air passes and acting by aspirator action to produce a partial vacuum at a location withdrawing by suction particles abraded from the work surface by said unit, said aspirator including a conduit forming and containing a passage, there being an opening through which a secondary flow of air and entrained abraded particles enter said passage generally transversely thereof, and means defining an inlet passage for said primary flow of air constructed to emit said primary flow at high velocity into said first mentioned passage at a location to flow rapidly across said opening and to draw said secondary flow of air and particles through the opening into said passage for admixture with the primary flow, said first mentioned passage having a non-circular cross section in the vicinity of said opening which is elongated in a relation giving said first mentioned passage a narrow width in a predetermined direction in which the opening faces into said first mentioned passage and a substantially greater width generally perpendicular to said direction, said first mentioned passage and conduit having said non-circular cross section for a substantial distance beyond said opening and then changing progressively to an essentially circular cross section. 